Studies on the mechanism of granulosa cell luteinization will be continued. Emphasis will be placed upon examination of control of maturation of gonadotropin receptors during follicular maturation in the rhesus monkey and pig. Granulosa cells will be grown in chemically defined media enriched with hormonal agents suspected as controlling LH and FSH receptor maturation. Porcine granulosa cells will be employed in conjuction with I125-labeled hCG as an assay system for LH - CG in the monkey, pig and other species.